from the attached link...
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Is bathing together normal in Japan?
Yes, in Japan parents and children bath together fully naked. And that's culturally perfectly normal. From a Japanese perspective, together tub-time is good for family bonding. As children grow older, they'll start enjoying bath time separately.
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Maybe not your cup of tea, but it works for them...
Link: https://emojicut.com/articles/is-bathing-together-normal-in-japan